Inductor for magnetic-pulse stamping of flat banks

ABSTRACT

An inductor for magnetic-pulse stamping of flat blanks comprises a cylindrical current-conducting frame having radial circular slot which accomodates a winding, whereas positioned in the proximity of one end surface of the cylindrical currentconducting frame is a flat blank, while the body of the frame has holes at the side opposite to the end surface in whose proximity a flat blank is positioned, the holes communicating with the nearest end surface by slits.

United States Patent Bely et al.

[45] Nov. 25, 1975 INDUCTOR FOR MAGNETIC-PULSE STAMPING OF FLAT BANKS [76] Inventors: Igor Vasilievich Bely, ulitsa Filed:

Nov. 15, 1974 Appl. No.: 524,307

[52] US. Cl. 72/56 [51] Int. Cl? B21D 26/14 [58] Field of Search 72/56; 335/299; 29/421 M [56] References Cited UNITED STATES PATENTS 3,231,842 l/l966 Brower 335/299 3,321,946 5/1967 Ferguson 72/56 3,372,566 3/1968 Schenk et al. 72/56 3,427,842 2/1969 Jansen 72/56 3,439,403 4/1969 Lippmann et al 72/56 Primary Examiner-Richard J. Herbst Attorney, Agent. or FirmHolman & Stern {57] ABSTRACT An inductor for magnetic-pulse stamping of flat blanks comprises a cylindrical current-conducting frame having radial circular slot which accomodates a winding, whereas positioned in the proximity of one end surface of the cylindrical current-conducting frame is a flat blank, while the body of the frame has holes at the side opposite to the end surface in whose proximity a flat blank is positioned, the holes communicating with the nearest end surface by slits.

2 Claims, 3 Drawing Figures U.S., Patent Nov. 25, 1975 3,921,426

INDUCTOR FOR MAGNETIC-PULSE STAMPING OF FLAT BANKS This is a continuation of application Ser. No. 432,649 filed Jan. ll, 1974, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates generally to shaping metals by the pressure of pulsed electromagnetic field and more specifically it relates to inductors for magnetic-pulse stamping of flat blanks.

There are known inductors for magnetic-pulse stamping of flat blanks, comprising a current-conduct ing frame whose radial circular slots accomodate a winding, and wherein one of the end surfaces of the current-conducting frame is a working one to serve for positioning a blank of flat sheet metal in the proximity of it.

A disadvantage of known inductors is that they are not enough effective for flat stamping because of a low actual efficiency.

This results from the fact that a considerable dissipation current flows in the non-working portion of the current-conducting frame of the inductor, namely, on the surface of the end portion of the inductor, opposite to the working one. This reduces the operating current flowing on the working end surface of the current-conducting frame of the inductor, but exactly this operating current determines the extent of electromagnetic pressure to be exerted on a blank. Thus, the working zone of the inductor is shunted by the non-working portion of its frame.

Apart from that, a disadvantage of known inductors is that due the non-uniform distribution of current over the working surface of the inductor a non-uniform deforming force exerted on a blank is created in the working zone of the inductor between its central and peripheral sections.

SUMMARY OF THE INVENTION The object of the present invention is to obviate the above disadvantages.

Another object of the present invention is to provide a high-efficiency inductor for magnetic-pulse stamping of flat blanks, having a higher actual efficiency and creating a more uniform deforming force exerted on a blank, as compared with uniform deforming force exerted on a blank, as compared with known ones, with simultaneous provision of a possibility for regulating the distribution of pressure in the center and periphery of the inductor working surface.

According to the invention these objects are achieved due to the provision of an inductor for magnetic-pulse stamping of fiat blanks, comprising a cylindrical current-conducting frame having a radial slot which accomodates a winding, while one of the end surfaces thereof serves for positioning in its proximity a flat blank to be treated, according to the invention, radial holes are made in the body of the cylindrical current-conducting frame of the inductor at the side opposite to the end surface in the proximity of which a blank is positioned, the holes being connected to the nearest end surface by means of slits.

In addition, it is expedient to provide axial holes in the central zone of the frame, the holes being communicated by means of slits.

Due to the fact that the non-working portion of the inductor frame is provided with radial holes communicated with the nearest end surface by means of slits. the inductance of this portion of the inductor is increased and electric shunting of its working zone is reduced. which considerably reduces the loss of energy .and upgrades the actual efficiency of the inductor as compared with known inductors.

The central zone of the inductor frame has axial holes communicated by means of slits, which creates a more uniform deforming force exerted on a blank and affords a possibility for regulating the force in the working zone of the inductor.

The above-mentioned inductor for magnetic-pulse stamping of flat blanks substantially broadens the field of application of the magnetic-pulse stamping method due to a possibility of its wide employment in mechanical engineering for treating flat sheet metal materials.

It is most profitable to use the inductor for such operations as punching-out, beading, creasing, cambering, etc., as well as for performing various assembling operations.

BRIEF DESCRIPTION OF THE DRAWINGS In order to make the invention more readily understood, a specific embodiment thereof will now be described with reference to the accompanying drawings. in which:

FIG. 1 is a schematic of the inductor for magneticpulse stamping of flat blanks, viewed from the side of the end surface in whose proximity a blank is positioned;

FIG, 2 is a cross-sectional view taken along the line IIII of FIG. 1, showing a blank, and a key diagram for connecting the inductor to the circuit of a magneticpulse outfit: and

FIG. 3 is a schematic of the inductor viewed from the side of the end surface opposite to the working one.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inductor for magnetic-pulse stamping (FIGS. 1, 2) comprises a cylindrical current-conducting frame 1 having a radial circular slot 2 which accomodates a winding 3.

A radial slit 4 is cut in the cylindrical current-conducting frame I, the slit being communicated with the slot 2 and with an end surface 5 in whose proximity a flat blank 6 is positioned.

In addition, axial holes 7-11 are made in the central portion of the cylindrical current-conducting frame 1, the holes being coaxial in relation to the body, while radial holes 13-20 (FIG. 3) are made in the body of the cylindrical current-conducting frame 1 in the proximity of an end surface 12 (FIG. 3) which is opposite to the end surface 5 (FIG. 1).

The axial holes are communicated by means of slits 21 (FIG. 1), while the axial hole 9 is additionally communicated with the radial slit 4.

Communication of radial holes 13-20 (FIG. 3) with an end surface 12 is effected by means of slits 22, while these radial holes 1320 are communicated with the radial circular slot 2 by means of the slit 4.

The winding 3 accomodated in the radial circular slot 2 is connected to an electric circuit including a bank of capacitors 23 and a switching device 24.

The inductor for magnetic-pulse stamping of flat blanks operates as follows.

At the moment the electric circuit is closed by the switching device 24 (FIG. 2), the bank of capacitors 23 discharges to the winding 3 of the inductor. This creates a pulse of current flowing through the winding 3 with resultant currents induced in the walls of the radial circular slot 2, the currents being shorted out through the slit 4 (FIG. 1) and through serially connected holes 7-11 and holes 13-20 (FIG. 3).

The current flowing over the end surface 5 (FIG. 2) and holes 7-11 induces in the blank 6 eddy currents which in cooperation with currents in the inductor exert power action on the blank 6. causing deformation of the latter.

The inductance ratio of the holes 7-11 and the end surface 5. through which the current is flowing. is chosen to be capable to ensure the required distribution of currents among them. The regulation of the ratio of the above inductances and the corresponding distribution of deforming forces are achieved through the selection of the number of holes and the value of their diameter.

The flow path of the operating current exerting the required power action on the blank is shown by arrows in FIGS. 1, 2. The current flowing through holes 13-20 (FIG. 3) adjacent to the end surface 12 is a dissipation current not participating in producing the power action exerted on the blank 6. Therefore. for the purpose of 4 reducing this current and corresponding increasing the operating current it is necessary to increase to a maximum the inductance of this portion of the inductor frame 1.

This latter requirement is fulfilled through the corresponding selection of the value of the diameter and the number of radial holes 13-20.

What we claim is:

1. An inductor for magnetic-pulse stamping of flat blanks. comprising: a cylindrical current-conducting frame having end surfaces. the geometrical form of one of said end surfaces. which comprises the working end surface. being adapted to the given profile or contour of the flat blank it adjoins. the opposite end surface having radial slits mutually communicating with radial holes provided in the body of said current-conducting cylindrical frame: a winding accommodated in a radial annular slot of said current-conducting cylindrical frame formed therein adjacent the side surface thereof between said radial holes and said working end surface.

2. The inductor for magnetic-pulse stamping of flat blanks as set forth in claim 1, wherein the central zone of said cylindrical current-conducting frame has axial holes communicated by slits with equalize and regulate deforming forces across the end surfaces. 

1. An inductor for magnetic-pulse stamping of flat blanks, comprising: a cylindrical current-conducting frame having end surfaces, the geometrical form of one of said end surfaces, which comprises the working end surface, being adapted to the given profile or contour of the flat blank it adjoins, the opposite end surface having radial slits mutually communicating with radial holes provided in the body of said current-conducting cylindrical frame; a winding accommodated in a radial annular slot of said current-conducting cylindrical frame formed therein adjacent the side surface thereof between said radial holes and said working end surface.
 2. The inductor for magnetic-pulse stamping of flat blanks as set forth in claim 1, wherein the central zone of said cylindrical current-conducting frame has axial holes communicated by slits with equalize and regulate deforming forces across the end surfaces. 